1. Field of the Invention
The present invention relates to a resin composition that has excellent wear properties and high flame retardancy and further to a resin molding that is obtainable by melt molding of such composition. In particular, the invention contemplates offering structural materials suited as component parts and casings for use in office automation equipment, household appliances and the like.
2. Description of the Related Art
For its excellent heat resistance, impact resistance and electrical characteristics as well as its good dimensional stability, a polycarbonate resin (hereinafter referred to as a PC resin where needed) has been widely applied to office automation equipment and household appliances especially at their respective portions which are subjected to sliding. Flame retardancy is also required for office automation equipment and household appliances, and therefore, much attention has been focused on making the PC resin nonflammable in nature.
In order to attain nonflammability of the PC resin, one technique is known which is contrived to add to that resin a flame retardant of a bromine type such as biphenyl bromide, tetrabromobisphenol A or the like as disclosed for example at page 242 of "Technique for Nonflammability of High Polymers and its Application" edited by Hitoshi Nishizawa. Another such technique is known in which a phosphate ester compound is incorporated in the PC resin as taught by Japanese Unexamined Patent Publication No. 4-300968.
However, though capable of giving improved flame retardancy to the PC resin, the aforementioned bromine type of flame retardant is liable to evolve dioxins during disposal and incineration of the associated used office automation equipment or household appliance. This eventually invites environmental pollution.
The phosphate ester compound noted above allows the PC resin to be highly flame retardancy but to such an extent that wear properties and impact strength are diminished.
On the other hand, there is proposed a PC-polyolefin resin composition comprised of a PC resin, a polyolefin resin, a modified polyolefin resin and an aminocarboxylic acid as found in Japanese Unexamined Patent Publication No. 8-157664. Such known composition is designed to avoid ply separation or delamination in an effective manner, which defect would be likely to take place when a PC resin and a polyolefin resin are made together into a molded product as by injection molding and because the two resins are, by nature, less compatible with each other. This composition, though highly slidable, is less nonflammable. Moreover, Japanese Examined Patent Publication No. 1-17501 discloses a resin composition comprised of a PC resin and an acrylonitrile-butadiene-styrene copolymer. This type of composition, like the above composition, is excellent in wear properties but unacceptable in flame retardancy.
As is apparent from the foregoing situation of the prior art, no PC type resin compositions have yet been feasible with a proper balance between wear properties and flame retardancy and on an industrial scale.